Child maltreatment (CM) constitutes a serious public health problem in the United States1 and is known to compromise children's developing self-regulation skills and amplify risk for substance use and other regulatory disorders. Parents are implicated in more than 80% of CM cases involving physical abuse and neglect and thus represent critical targets of intervention. Research on the physiological response of CM parents during parenting suggests that parenting interventions may be less effective with this population2 because they fail to affect the neurobehavioral markers of dysregulation that drive harsh, aversive parenting. Parent-Child Interaction Therapy (PCIT), an intensive, 20-session parenting intervention, has been shown to improve the quality of CM parenting, improve positive parenting and child behavior, and produce declines in CM recidivism,3,4 though the mechanisms underlying its effects are little understood. On the basis of its live- coached, moment-by-moment scaffolding of positive parenting, we theorize that PCIT builds regulatory strength in parents, which then supports lasting behavior change. Use of bug-in-the-ear technology-unique to PCIT-provides parents with immediate access to therapist reinforcements for positive parenting that work to counter parents' heightened physiological arousal, inhibit (prepotent) aversive responding, and support greater use of (nondominant) positive parenting behavior. This study is designed to extend the collective work of our investigative team. It uses an experimental intervention design as a vehicle for testing a causal model of change in neurobehavioral indices of self-regulation. Specifically, we propose to conduct a randomized, controlled trial of PCIT for CM and test the effects of PCIT on self-regulation and behavior in CM parents and their elementary-school children. Two hundred-fifty (250) maltreating mothers and their children (age 5-8 years) will be drawn from Child Protective Services and randomized to the PCIT intervention or a control condition (services as usual). Key contextual risk factors will be assessed, including cumulative risk, parent mental health, and parent substance use. A multirater, multimethod approach to assessment will include neural (EEG/ERP), physiological (ECG), behavioral, and self-report measures of self-regulation in CM mothers and their children, as well as standard measures of parenting skills and children's behavior outcomes. Families will be followed at 6 months for self-regulation, parenting, and child behavioral outcomes, and to 1 year for CM recidivism. Findings from this proposed study are expected to have significant implications for optimizing CM parenting interventions by (a) determining the sensitivity of CM parent and child neurobehavioral self-regulation systems to intervention, and (b) identifying individual differences in self-regulation that mediate and moderate response to intervention and long-term maintenance of gains.